On Mon, Nov 26, 2012 at 05:51:16PM -0500, J. Bruce Fields wrote:
> On Mon, Nov 26, 2012 at 05:38:49PM -0500, Chuck Lever wrote:
> > What exactly is the problem with the current code?
> >
> > client_resolve() can return a NULL in some cases. Why is it OK to
> > pass a NULL "ai" to client_compose() ? Looks like that can result in
> > a mountd segfault.
>
> Bah, I thought I'd checked this and found it was prepared to handle
> that, but no:
>
> client_check->check_wildcard()
>
> looks like it can oops.
Right, so the real problem is just that we're skipping the downcall on
failure instead of responding with a negative cache entry. Thus we're
leaving the client hanging instead of returning an error.
So, I suppose we should do the below, based on steved's suggestion
(compiled, otherwise untested).
--b.
commit dfb31d861261c8461a2dc4fb7e8823f5169a9079
Author: J. Bruce Fields <bfields@xxxxxxxxxx>
Date: Tue Nov 27 16:10:41 2012 -0500
mountd: auth_unix_ip should downcall on error to prevent hangs
Since bf6a4febaa78bf188896b7b5b02c46562dd08b70 "mountd: handle
allocation failures in auth_unix_ip upcall", a failure to map the
address of an incoming client to a name could result in a hang.
We should be responding with an error in the case, not just skipping the
downcall and leaving everybody hanging.
Signed-off-by: J. Bruce Fields <bfields@xxxxxxxxxx>
diff --git a/utils/mountd/cache.c b/utils/mountd/cache.c
index e950ec6..c13f305 100644
--- a/utils/mountd/cache.c
+++ b/utils/mountd/cache.c
@@ -109,12 +109,10 @@ static void auth_unix_ip(FILE *f)
struct addrinfo *ai = NULL;
ai = client_resolve(tmp->ai_addr);
- if (ai == NULL)
- goto out;
- client = client_compose(ai);
- freeaddrinfo(ai);
- if (!client)
- goto out;
+ if (ai) {
+ client = client_compose(ai);
+ freeaddrinfo(ai);
+ }
}
qword_print(f, "nfsd");
qword_print(f, ipaddr);
@@ -127,7 +125,6 @@ static void auth_unix_ip(FILE *f)
xlog(D_CALL, "auth_unix_ip: client %p '%s'", client, client?client: "DEFAULT");
free(client);
-out:
freeaddrinfo(tmp);
}
--
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